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From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [Qemu-devel] [PATCH] virtio-net: Remove RX_EXTRA feature
Date: Mon, 15 Jun 2009 14:48:13 +0930
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To: Alex Williamson <alex.williamson@hp.com>
Cc: markmc@redhat.com, qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>

On Sun, 14 Jun 2009 11:01:37 pm Alex Williamson wrote:
> On Sun, Jun 14, 2009 at 3:39 AM, Michael S. Tsirkin<mst@redhat.com> wrote:
> > On Fri, Jun 12, 2009 at 01:17:04PM -0600, Alex Williamson wrote:
> >> No need to use a feature bit to identify the RX modes.  The guest
> >> will get an error back if the backend doesn't support these controls.
> >>
> >> Signed-off-by: Alex Williamson <alex.williamson@hp.com>
> >
> > What's the motivation here - are we running out of feature bits already?
> > Using feature bits for everything makes the interface more consistent
> > and IMO easier to use.
>
> See the thread starting here:
>
> http://lists.gnu.org/archive/html/qemu-devel/2009-06/msg00519.html
>
> Both Rusty and Mark voted against the feature bit.

Not quite.  I was unclear.  I support the use of a feature bit.  My question 
is more meta.

Features do need justification.  (Not much, but some).  It's hard to see the 
use case where this feature offers significant advantages over promisc.  Without 
that, I'd wait until someone reports a need.

Thanks,
Rusty.